How much more powerful would this be

I do not currently own a mac but am in love with the OS and really want to buy one. Im not really strapped with cash at the moment and I dont want the mini or an imac. I did some searching on ebay and found a mac pro priced at $1100.

2 Quad-core Xeons? Yeah, that's powerful. Put it to good use, though, and pilot some space ships. Or perhaps you could control 300 remote control cars in a mini city, and have them all obey traffic laws. Or both, while listening to music.

You can probably upgrade them if you really want to. After all, they'll be slightly obsolete in 10 years or so.